I have an older 101# Maxxum. Bought the boat about 2 months ago, and it worked fine at first.

Now it seems like whatever tells the motor how fast to turn isn't working properly. When I first got it, it felt like it would ramp up to the speed I had it set at and I thought maybe that was just normal. Now sometimes it does that, sometimes it barely turns at all, sometimes I can feel the speed going up and down. Does it more at lower speed, 30-50%. If I turn the speed up, 60-80% it works great and then usually starts working at the lower speeds fine for a while too.

I don't think it's a battery problem. Anyone else ever have an issue like this?

The first thing that would come to my mind is water inside the lower unit. You might have gotten something wrapped behind the prop or it was already dried out when you bought it. The seals could be so old that they have deteriorated and failed. Other than that you could have a corroded commentator on the armature. The only other thing I could think of would be a battery issue but that's a very small chance.

Where are you located? I could take a look at it for you if you'd like.

I think you may have the pot going out in the foot control. The problem there is the thing is part of the board and they don't sell the thing by itself.

I found one that works. Looks like

When you look at yours, read the specs and see if its like mine. A 1k ohm pot. My problem was with an old 74 pound thrust motor.

You have to take the speed control off, a clip and the thing comes off, easy. Then you cut the wires and splice this in. My 15 year old Maxxum did just like yours. Irregular at low speeds, seemed above 50 percent and it worked good. After the replacement all was good.

Try taking a look at the pot. Its easy to see. What happened on mine was the area around where the wires attached to it started coming loose. The MK pot looked just like this one, was like this one other than it had silicone where it attached to the cable. That was physically coming loose. I could push it back and hold it just right and the thing worked just fine. Let it go and it was back to the symptoms you described.

Good Luck. I can give you the exact part number but if you take the yours loose it has that information on it. Its under 10 bucks for the part.